Many types of industrial facilities, such as for example, steam power plants, require condensation of the steam as integral part of the closed steam cycle. Both wet and dry type cooling towers have been used for condensing purposes. Wet cooling towers are preferred when sufficient water resources are available as wet cooling is more energy efficient than dry cooling. However, as wet cooled systems consume a considerable amount of cooling water, dry cooling systems have gained a growing market share because of their ability to save water resources. In particular, forced draught dry air-cooled condensers consisting of a multitude of fin tube heat exchangers have been known for many years. Contrary to wet cooling arrangements, which are characterized by a secondary cooling water loop, these systems are so-called “direct” dry systems where steam is directly condensed in the fin tube heat exchangers by air cooling. The fin tube heat exchangers are mounted with the tube center lines arranged in a position inclined to the vertical direction. The bundles are mounted to a support structure which enables cooling air to be conveyed through the fin tube heat exchangers by means of fans. Ambient air in contact with the fin tube heat exchangers condenses the steam inside the fin tubes, which then exits the heat exchanger as condensed sub-cooled liquid. Although being commercially successful over many years, a disadvantage of direct dry air-cooled condensers is the power required to operate the fans, as well as fan noise, which is undesirable in most situations. Currently two types of dry cooling are used, air-cooled condenser (ACC) natural draft or fan assisted, and indirect dry cooling tower (IDCT) natural draft or fan assisted.
In an indirect dry cooling system, a turbine exhaust condenser is provided, where turbine steam is condensed by means of cooling water. The cooling water is conveyed through a water duct by means of a pump to an air-cooled cooling tower. An indirect dry cooling tower consists of a multitude of air-cooled heat exchangers where the heat is conveyed to the ambient air by convection. The cooling tower may be operated with fan assistance or in natural draught. The turbine exhaust condenser may for example be a surface or a jet condenser. Because of the presence of a secondary water loop, indirect dry cooling systems are not as thermally effective as direct dry systems. Another disadvantage of natural draught indirect dry cooling systems, however, is the higher investment cost as compared to the forced draught direct air cooled condenser.
These natural draft cooling towers are generally from 100 meters to 200 meters high or more and 75 to 150 meters or more in diameter. In general, the larger the towers are, the more heat they are capable of dissipating. However, if the plant is modified to produce more energy or otherwise need more cooling capacity, it is very difficult to increase capacity to a natural draft cooling tower. Adding heat transfer media whether wet or dry may not increase cooling. By adding depth to the heat exchangers the resistance to air flow is increased. The total airflow through a natural draft tower is reduced and thermal performance may actually be diminished. More airflow may be needed to increase thermal performance.
Accordingly, it is desirable to provide a system and method to increase the cooling capacity of a cooling tower that is capable of overcoming the disadvantages described herein at least to some extent.